Several methods are known for fire-sealing lead-throughs for cables and/or wires through building components. Most of these methods have in common that they are preferably intended for walls of concrete. Usually these methods require a careful planning of the running of the cable and/or the wire, as these methods mean that complete lead-throughs or mounting frames for such are moulded onto the building components. In the cases when complete lead-throughs will be used for moulding, these are preferably made of a corrugated pipe covering of plastic which is filled with an elastic fire-resistant foam material. By means of a special tool, cables and/or wires are run through the foam, for example, according to the method which is described in Swedish patent No. 412 795.
According to another method, mounting frames are moulded into the building components as mentioned above. After the cables and/or wires have been run through the space in a frame this is filled with premanufactured fire-resistant pass pieces or with a fire-protective substance.
Also known are methods to achieve fire-proof lead-throughs in already existing moulded building components. In Swedish patent application No. 426 122 a method and an apparatus are described to place, in a hole made later in a building component, an elastic body of a fire-resistant foam material, said body having a considerably larger diameter than the hole. According to the patent application the body is compressed in the tool when being inserted in the hole and remains in place by compression transversely to the longitudinal direction of the hole, said compression being a condition for the intended functioning of the lead-through. Due to the high costs of the fire-resistant foam material, the body generally does not fill the whole length of the hole but the length of the body is adjusted to the fire class of the wall in question.
The fact that light building techniques are employed with increasing frequency and that fire classed partitions are made of a frame work of plates covered on either side with several layers of plaster board and having the space between the wall sides mostly filled with mineral wool, a need has arisen to be able to effectively fire-seal lead-throughs in such frame-work walls. None of the above mentioned known arrangements for lead-throughs can easily be placed in an optional position in a frame-work wall. To be able to place the lead-through in an optional position means that it does not have to be placed in connection to, and to be carried by, a latch or a nogging piece connecting the latches. This optional placing furthermore means that the lead-through will completely be carried by the surface covering of the wall, preferably made of plaster boards. When there is a fire, the plaster boards facing the fire center will successively be destroyed. In order to delay as much as possible this destruction due to the heating, it is important that the wall not be exposed to other strains than those caused directly by the fire. Due to the heating there are certain movements in the plaster boards, whereby a lead-through, which rigidly joins the two outer surfaces of the wall, can give rise to cracking of the plaster boards and rapid deterioration of the wall. Therefore, a lead-through must have a certain movability while when it is exposed to the heat from a fire-center it, must be tight and prevent hot fire-gases as well as poisonous and/or corrosive gases from the fire from passing through the lead-through.